Mykhailo Podolyak, an adviser to president Volodymyr Zelensky, who is leading talks with Moscow said such concessions would backfire as Russia would hit back harder after any break in fighting.
“The war will not stop. It will just be put on pause for some time,” Mr Podolyak said in an interview with Reuters in the presidential office in Kyiv.
“They’ll start a new offensive, even more bloody and large-scale.”
“The [Russian] forces must leave the country and after that the resumption of the peace process will be possible,” Mr Podolyak said, referring to recent calls from US defense secretary Lloyd Austin and Italian prime minister Mario Draghi for an immediate ceasefire as “very strange”.
Kyiv’s stance has become increasingly uncompromising as Russia has experienced military setbacks and as Ukrainian officials grow worried they might be pressured to sacrifice land for a peace deal.
“The war must end with the complete restoration of Ukraine’s territorial integrity and sovereignty,” Andriy Yermak, Ukraine’s presidential chief of staff said in a Twitter post yesterday.
Polish president Andrzej Duda offered Warsaw’s backing, saying the international community had to demand Russia’s complete withdrawal and that sacrificing any territory would be a “huge blow” to the west.
“Worrying voices have appeared, saying that Ukraine should give in to [President Vladimir] Putin’s demands,” Mr Duda said, the first foreign leader to address the Ukrainian parliament in person since Russia’s invasion.
“Only Ukraine has the right to decide about its future,” he said.
Speaking to the same session, Mr Zelensky renewed a plea for stronger sanctions against Moscow.
“Half-measures should not be used when aggression should be stopped,” he said.
His comments come as Vitaly Savelyev, a Russian transport minister, admitted sanctions against Russia had caused serious logistical problems in the country.
Mr Savelyev is reported to have told state media the measures had “virtually wrecked” Russian trade logistics and said Moscow had been forced to look for new trade corridors as sanctions had hit its operation on standard shipping routes to Asia.
The world’s three biggest shipping companies, MSC, Maersk and CMA CGM, are all blocked from trading with Russia due to sanctions.
Meanwhile, Russia continued its major offensive in Luhansk, one of two provinces in Donbas, after ending weeks of resistance by the last Ukrainian fighters in the strategic southeastern port of Mariupol.
The heaviest fighting focused around the twin cities of Sievierodonetsk and Lysychansk, interior ministry adviser Vadym Denysenko told Ukrainian television on Sunday.
The cities form the eastern part of a Ukrainian-held pocket that Russia has been trying to take over since mid-April after failing to capture Kyiv and shifting its focus to the east and south of the country.
Serhiy Gaidai, the governor of Luhansk, said in a local television interview that Russia was using “scorched-earth” tactics in the region.
“They are wiping Sievierodonetsk from the face of the Earth,” he said.
Russian shelling and “heavy fighting” near Sievierodonetsk has also continued, but the invading forces have failed to secure the nearby village Oleksandrivka, a Ukrainian military statement said.
Russia’s defence ministry said on Sunday its forces pummelled Ukrainian command centres, troops and ammunition depots in Donbas and the Mykolaiv region in the south with air strikes and artillery.
But in a victory for Ukraine forces, the Moscow-appointed head of the occupied Ukrainian town Enerhodar, next to the Zaporizhzhia nuclear power plant, was injured in an explosion on Sunday.
Andrei Shevchuk has been in intensive care following the attack, Russia’s RIA news agency reported, citing a source in the emergency services.